Question: Simplify the following expression: $n = \dfrac{5r + 6}{4r + 7} \div \dfrac{1}{9}$
Solution: Dividing by a number is the same as multiplying by its inverse. $n = \dfrac{5r + 6}{4r + 7} \times \dfrac{9}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $n = \dfrac{(5r + 6) \times 9} {(4r + 7) \times 1}$ $n = \dfrac{45r + 54}{4r + 7}$